(1) Field of the Invention.
This invention relates to a mining machine of the so-called continuous miner type used for the winning of minerals and/or for the driving of underground roadways or tunnels.
(2) Description of Prior Art
Continuous miners comprise a self-propelled chassis usually incorporating endless tracks, with a pair of spaced-apart, forwardly directed, parallel support arms pivotally attached at one end to the chassis and at the other end rotatably supporting a transverse shaft on which is mounted one or more rotary cutting drums provided with a plurality of picks, (the usual configuration being a central drum between the two arms, and an end drum beyond each arm), with a power train extending along each support arm to the shaft to rotate the drums, and with the arms being elevatable by hydraulic rams under the control of a machine operator.
For shearer type mining machines it has long been conventional to provide a water supply internally to the rotary cutting head for various advantageous purposes such as pre-start warning, dust suppression, pick cooling, incendive sparking suppression and/or air flow, but with continuous miners there is no ready access to introduce a water supply. With the construction proposed in GB 2296271 two half-shafts are employed, and a water supply route is down each arm, but the use of a relatively large diameter water seal, with resulting relatively high peripheral speed and rate of wear has been unavoidable. With other continuous miners water supply internally to the cutting drums has been avoided and such machines have been provided with a simple but less effective, spray bar intended to direct water spray to the vicinity of the rotary cutting drums.
One prior art proposal for introducing water externally to the cutting drums of continuous miners whereby any leakage or seal failure is not catastrophic as far as bearings and gearing is concerned because leaking water simply falls to the mine floor rather than contaminates bearings, gearing etc., is described in GB 2297989, but again a relatively large diameter water seal is unavoidable. Large diameter mechanical seals are also unavoidable in GB 2296271.